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[Xen-devel] [PATCH] clocksource=tsc

To: "Xen-Devel (E-mail)" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxxx>, "dan.magenheimer@xxxxxxxxxx" <dan.magenheimer@xxxxxxxxxx>
Subject: [Xen-devel] [PATCH] clocksource=tsc
From: "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>
Date: Sat, 12 Jul 2008 15:38:24 -0600
Cc: Dave Winchell <dwinchell@xxxxxxxxxxxxxxx>
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Attached patch adds clocksource=tsc boot option that
uses TSC as clocksource.  This option should only be
used on machines where TSC is known to be synchronized
across all processors.  A future TODO is to dynamically
determine if this is the case.

TSC may "beat" with another clocksource, resulting in
cross-processor Xen system time skew.  This skew can
be visible in PV guests and can appear as "time is stopped"
in hvm guests.  On some systems, this patch can reduce skew
by 30x or more.

Signed-off-by: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>

===================================
Thanks... for the memory
I really could use more / My throughput's on the floor
The balloon is flat / My swap disk's fat / I've OOM's in store
Overcommitted so much
(with apologies to the late great Bob Hope)

Attachment: tscstable.patch
Description: Binary data

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